Through DNA cloning and sequence studies, the encoded viral gene products of selected arenaviruses will be determined and correlated by protein/peptide sequence studies to the major structural and non-structural virus induced proteins. The data will be used as the basis for defining the transcription and translation strategies of the viruses, the function and relationship of monocistronic and polycistronic mRNA species, investigating models for virus persistence and the reasons for the observed non-reciprocal reassortment. Analyses are proposed using the cloned DNA representing different parts of the viral genome (e.g., the individual information for N, G1, G2 and L, plus any non-structural gene products) to determine their transcription strategies. Also experiments will be undertaken to define the translation and protein processing strategies of arenaviruses. For example, the question of whether both monocistronic and polycistronic mRNAs are formed will be determined and whether there is polar translation. In part these questions will be analyzed by using amber mutants and characterizing the viral induced mRNA species. Similar studies of viral RNA obtained from persistently infected cultures will be undertaken in order to understand the molecular basis of arenavirus persistence. It is postulated that the regulation of mRNA transcription (e.g., the attenuation of polycistronic mRNA synthesis) may be involved in the development and maintenance of persistence. Particular attention will be paid to characterizing defective viruses and other subgenomic RNAs and defining their relationship to the onset and maintenance of persistence. Selected members of the Arenaviridae (e.g., Pichinde, lymphocytic choriomeningitis virus, Tacaribe and alternate isolates of these and other arenaviruses) will be used to analyse their genetic compatibilities and derive intertypic, or interspecies, reassortant viruses. A model to explain non-reciprocal reassortment involving intersegment liasons will be investigated. Cloned viral glycoprotein information will be inserted into eukaryotic vectors to study glycoprotein expression. By site specific mutagenesis it is proposed to determine the effects of amino acid substitution in a neutralizing antibody recognizing epitope and what parts of the glycoproteins are important for intracellular processing and viral morphogenesis.